State the principle of working of ocean thermal conversion plant. Explain how the plant works ? Write one essential condition for it to operate properly.

Explanation

The energy avaible due to the difference in the temperature of water at the surface of the ocean and at deeper levels is called Ocean Thermal Energy (OTE).
Condition for it to operate properly :
Ocean thermal energy plants can operate if the temperature difference between the water at the surface and water at depths upto 2 km is 293 K `(20^(@)C)` or more.
Working. The devices used to harness ocean thermal energy are called ocean thermal energy conversion power plants (or OTEC power plants). A temperature differnece of `20^(@)C` (or more) between the surface water of ocean and deeper water is needed for operating OTEC power plants. In one type of OTEC power plant, the warm surface water of ocean is used to boil a voltatile liquid like ammonia or a CFC. The high pressure vapours of liquid are then used to turn the turbine of a generator and produce electricity. The colder water form the deeper ocean is pumped up to cool the used up vapours and convert them again into a liquid. This process is repeated again and again.